中国城市土地经济密度的分布动态演进

研究目的:探究城市土地经济密度的整体分布特征及其演进规律,为实现城市土地利用系统与城市社会经济系统的高效融合及协调发展提供指导与参考。研究方法:核密度估计,马尔科夫链。研究结果:(1)中国城市土地经济密度的整体水平不断提高,但存在着显著的空间非均衡特征,基本呈现出东部地区中部地区西部地区的地理格局;(2)在全国层面和东、中、西部三大区域层面,城市土地经济密度的地区差距在样本考察期内都不断加剧,且各地区城市土地经济密度在发展过程中都出现过不同程度的极化现象;(3)中国不同水平城市土地经济密度之间的流动性较差,各省份在总体城市土地经济密度分布中的相对位置比较稳定,且城市土地经济密度的长期均衡状态将处于中高水平和高水平。研究结论:采取差异化的城市土地利用管控策略和经济调控策略,实现东部、中部和西部地区城市土地利用与经济发展的协同共进。     

合肥市产业结构与土地经济密度的关联协调研究

研究目的:探讨合肥市产业结构与土地经济密度的内在关系及相互作用,为区域产业结构调整优化和土地利用规划提供参考。研究方法:灰色关联度模型,协调度模型。研究结果:产业结构合理化和产业结构高级化对土地经济密度的影响作用显著;劳动生产率与土地经济密度的增长幅度一致时,二者的关联性强;第二产业占比大于第三产业且超出范围较小时,产业结构高级化水平仍较高;产业结构和土地经济密度保持较高关联、协调性时,二者相互促进。研究结论:在一定的经济发展阶段产业结构与土地经济密度密切相关,通过调整劳动生产率增速、GDP增速和各产业占比状况,能使二者的相互促进作用达到最优。     

Economies of traffic density and scale in the integrated air cargo industry: The cost structures of FedEx Express and UPS Airlines

This paper examines the cost structures of the leading integrated air cargo carriers, FedEx Express and UPS Airlines. A total cost model is estimated for the two carriers using quarterly data on domestic operations and costs over a nine-year period (2003–2011). The estimated model indicates that the integrated industry exhibits increasing returns to traffic density and constant returns to scale. Accounting for carrier-specific differences in cost structure and network size, FedEx Express is found to be more cost-efficient than UPS Airlines. Looking at the carriers individually, UPS Airlines exhibits substantial economies of traffic density and constant returns to scale while FedEx Express' cost structure is characterized by weak economies of density and constant returns to scale. The combined effect of returns to density and returns to scale on the cost structures of integrated carriers is captured by economies of size. Both FedEx Express and UPS Airlines exhibit economies of size, indicating that carriers in the integrated industry can be more cost efficient by making appropriate adjustments to their network size as their output grows. Moreover, the relative cost-efficiencies of the carriers are reversed when their network-size differences are not controlled.     

一种基于自适应相似矩阵的谱聚类算法

为了消除在构建谱聚类算法的相似矩阵时,高斯核函数中尺度参数的波动影响,构建了一种自适应相似矩阵,并应用到谱聚类算法中。自适应相似矩阵中数据点间的距离度量采用测地距离算法,相距较近的两点间的距离近似于欧氏距离,相距较远的两点则先根据欧氏距离得到每个数据点的k个近邻点,然后累加近邻点的测地距离,由此得到每对数据点间的最短距离。两点间的局部密度用共享近邻的定义来表示,更好地刻画了数据集的本征结构。在5个人工数据集和国际通用UCI数据库中的5个真实数据集上进行实验。实验结果表明,所提算法的聚类准确率高于对比算法的准确率,对复杂分布数据有很强的自适应能力。研究成果为数据挖掘及机器学习提供了思路和方法。     

基于模态应变能密度理论的网架结构损伤识别方法

为了研究网架结构的损伤检测方法,根据应变能密度理论,提出采用单元模态应变能密度差值作为网架结构损伤识别指标的方法,以损伤单元模态应变能密度差值的大小初步确定单元的损伤程度。分析了5种具有代表性的损伤工况,并在数值计算结果中引入了白噪声。结果显示,在一阶模态下,针对单损伤、多损伤和轻微损伤、严重损伤等不同损伤工况,损伤杆件的模态应变能密度差值均为高值。因此,该方法可以有效识别出网架结构的损伤位置,根据损伤单元的模态应变能密度差值大小初步确定单元的损伤程度,且在一定的噪声水平下具有较强的鲁棒性,对网架结构损伤识别具有参考价值。     

环渤海地区区域经济空间网络关联结构研究

采用网络分析方法,对1995—2014年环渤海地区区域经济空间网络关联结构进行分析,研究发现：环渤海地区区域经济空间网络关联特征显著,分为“辽宁”和“京津冀鲁”两个子网络;网络密度稳步上升,但仍然较低;核心区域的经济比重有所降低,但份额始终较大;网络效率在波动中趋降,空间溢出效应趋于显著。其中,北京、天津、济南等9地属于“主受益”板块,石家庄、保定、潍坊等19地属于“经纪人”板块,沈阳、大连、鞍山等4地属于“双向溢出”板块,而秦皇岛、承德、葫芦岛等12地属于“净溢出”板块。产业结构转型升级、控制FDI区域差异以及投资多元化等有利于环渤海地区增强区域经济空间关联。应多途径构建区域经济关联通道,打造“环型”网状关联经济,并通过产业转型升级和经济多元化发展增进区域经济空间关联。     

Assessing recreation carrying capacity of the environment attributes based on visitors’ willingness to pay

Recreation carrying capacity (RCC) is one of the most important indictors used in measuring the usage limits for the forest park resources. However, the consensus has not been reached with respect to the RCC’s content and its measuring metrics. In this paper, we attempt to establish a new RCC theoretical framework based on the demand theory of the tourism product characteristics. In the process, the choice experiment and orthogonal design methods are used in questionnaire designs and the conditional Logit model is used for parameter estimates. More than 700 park visitors are surveyed for data collection at the Shenyang National Forest park of Liaoning province in China. The primary park attributes being considered encompass vegetation, coverage, water quality, number of rubbish on the park trail path, admission fees, and congestion. The carrying capacity threshold for each specific attribute is identified.     

An analysis of snow options for ski resort establishments

This study proposes a pricing method for put options on snow level for tourism establishments operating in Palandoken ski resort in the east of Turkey. In the calculation of put prices historical densities and Edgeworth adjusted densities methods together with Alaton, Djehiche, and Stillberger (2002) method have been applied. The findings show that there may be significant differences in the prices calculated by the three different methods, hence enabling both parties, i.e. buyers and sellers, with bases in the negotiation process. As the study is primarily aimed at providing a framework for pricing put options on snow levels in general, it is expected that it would be of use not only for this particular ski resort but also for various ski resorts in the world.     

电子政务价值评估流程——以公众为角度

经过这些年的发展,政府公务员、电子政务项目的开发者、公众都发现我国的电子政务建设缺乏相应的绩效评估机制,从而导致了政府部门的盲目投入和盲目建设现象的发生。为了促进我国电子政务又快又好的发展,可以以经济学作为电子政务价值评估的基础,在此基础上提出基于公众角度电子政务价值评估的内涵,并设立相应的评价方法以及评价的意义。     

高密度电法在地基塌陷区勘察中的应用

通过高密度电法快速采集地电断面结构信息，准确反映不良地质体的二维分布情况。为查明地基塌陷的诱发原因和地基处理提供了依据。通过实例证明该方法工作效率高、信息量大及在实际应用中的良好效果。